This invention relates to railroad couplers. More particularly, it relates to what are called square butt couplers, which are usually of the so-called E type. Couplers of this type are used on cars with conventional trucks and, more recently, on cars with single axle trucks. Examples of cars with single axle trucks are found in application for U.S. Pat., Ser. No. 409,844 filed Aug. 20, 1982, now abandoned; application for U.S. Pat., Ser. No. 597,642 filed Apr. 6, 1984, now U.S. Pat. No. 4,589,558; application for U.S. Pat., Ser. No. 653,821 filed Sept. 24, 1984; and application for U.S. Pat. Ser. No. 653,831, filed Sept. 24, 1984, now U.S. Pat. No. 4,596,311; all of which are owned by the common assignee. The disclosure of these applications are hereby expressly incorporated by reference into this application.
In a conventional square butt coupler, the rear part of the square butt coupler shank has considerable latitude for lateral movement. On cars with single axle trucks, this can result in unfavorable coupler angles with respect to the car center line under certain train operating conditions.